The Battle for Wesnoth
The Battle for Wesnoth (or just Wesnoth) is a strategy video game. It is designed by David White and the first released was made in June 2003. The game is available under the GPL license. The 1.14.5 version is the last release and was made the 18 September 2018.
The project has a very big community and counts many contributors too. Some developers are well-known authors of other free and open-source projects. For example, there are Eric S. Raymond or Rusty Russell.
The game is translated in more than 50 languages. In 10 of them, the game is very well translated (These languages have more than 95% of messages translated).